Resilient coil spring adjuster and method of fabrication

ABSTRACT

A device for use in coil springs, such as vehicular suspension springs, to operate as a spring lifter, to eliminate sag by restoring spring function, and/or to convert a standard coil spring to a variable rate coil spring, being formed from one or more strips of resilient material formed with ends adapted to engage facing surfaces of adjacent coils and an intermediate flexible portion arced to resiliently resist compression of the coil spring. Multiple strips are shown formed with their midportions joined by wire or by integral connectors so that they are spaced around the coil spring as necessary. Any number of strips may be used on a spring and in various vertical locations to provide lift, spring reinforcement, or selective variable spring rate where desired. Two, three or more strips may be connected together in manufacture, and separated by severing the connector when desired. One form of such an adjuster strip may be fabricated in a nowaste production process by cutting from a sheet of material a plurality of identical members in which each member has spaced leafs integrally joined by connector portions and complementary with the spaces between the leafs of adjacent members, after which the leafs are bent to form the ends of the strips and the connector portions are bent to locate the spaced strips along the helix of the coil spring with which they are to be used.

United States Patent Wehner Feb. 18,1975

[ RESILIENT COIL SPRING ADJUSTER AND METHOD or FABRICATION [75] Inventor: William C. Wehner, Inkster, Mich.

[73] Assignees: Howard E. Crawford, Dearborn; Robert C. Hauke, Holly, both of, Mich.

[22] Filed: Apr. 2, 1973 [21] Appl. No.: 346,759

[52] US. Cl. 267/61 S [51] Int. Cl Fl6f 1/12 [58] Field of Search 267/61 S, 61 R [56] References Cited UNITED STATES PATENTS 2,703,234 3/1955 Tapp 267/61 S 2,829,883 4/1958 Copeland 267/61 S 3,034,777 5/1962 Osterhoudt 267/61 S FOREIGN PATENTS OR APPLICATIONS 978,240 12/1964 Great Britain 267/61 S Primary Examiner-Even C. Blunk Assistant Examiner]effrey V. Nase Attorney, Agent, or Firm-l-Iauke, Gifford, Patalidis & Dumont [57] ABSTRACT A device for use in coil springs, such as vehicular suspension springs, to operate as a spring lifter, to eliminate sag by restoring spring function, and/or to convert a standard coil spring to a variable rate coil spring, being formed from one or more strips of resilient material formed with ends adapted to engage facing surfaces of adjacent coils and an intermediate flexible portion arced to resiliently resist compression of the coil spring. Multiple strips are shown formed with their mid-portions joined by wire or by integral connectors so that they are spaced around the coil spring as necessary. Any number of strips may be used on a spring and in various vertical locations to provide lift, spring reinforcement, or selective variable spring rate where desired. Two, three or more strips may be connected together in manufacture, and separated by severing the connector when desired.

One form of such an adjuster strip may be fabricated in a no-waste production process by cutting from a sheet of material a plurality of identical members in which each member has spaced leafs integrally joined by connector portions and complementary with the spaces between the leafs of adjacent members, after which the leafs are bent to form the ends of the strips and the connector portions are bent to locate the spaced strips along the helix of the coil spring with which they are to be used.

3 Claims, 1.4 Drawing Figures PATENTEU FEB] 81975 SHEET 2 BF 2 RESILIENT COIL SPRING ADJUSTER AND METHOD OF FABRICATION BACKGROUND OF THE INVENTION A. Field of the Invention The present invention relates to devices adapted to compression coil springs such as vehicular suspension springs, for altering or improving their functional characteristics.

B. Description of the Prior Art The most common uses of such devices are in attempting to cure vehicular suspension spring sag and increase the ability of springs to carry higher loads than those for which they were designed. These devices are ordinarily called spring lifters.

One type of inexpensive spring lifter is a solid metal block which is grooved to engage adjacent spring coils and prevent them from compressing. Any number of these may be used depending upon the amount of lift desired. Their major disadvantages are that they are difficult to install, they tend to be dislodged during heavy spring bouncing, and they tend to concentrate loading on local areas of the spring which may initiate breakage.

Attempts to facilitate easier installation of such devices generally aim toward the use of mechanically adjustable blocks, but these are more costly and still cause excessive local stresses.

Compressible rubber blocks have also been used, solving problems of localized overloading, but they are still difficult to install and are readily dislodged.

Inflatable devices have also been used to add to the spring loading capacity, but their cost is high and they require pressure checking and reinflation at times.

The above are alternatives, in vehicles, to installing shims under the springs which involve rather high labor costs due to the time involved.

SUMMARY OF THE INVENTION My invention is intended to solve the problems of spring sag by restoring spring function and/or operate to convert a standard to a variable rate coil spring. In so doing, the problems enumerated in the foregoing are eliminated.

In structure, the device of the present invention comprises an element formed from a strip of resilient material, preferably metal, which has an arced medial portion and ends adapted to engage facing portions of adjacent spring coils, to there by resiliently resist compression between the coils. Multiple strips are joined by wire or integral connecting members which are formed to the helix of the spring in which the device is intended to be installed.

The ends of the strips are formed to fit the spring coil for retention thereby, and are dimensioned for easy installation when the coil spring is unloaded.

Another aspect of the invention is the manufacture of the devices using a no-waste process, the strips being cut in multiple members having edge contours which are complementary to each other so that only shavings from the side edges of an endless length of stock will be scrapped.

DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention may be had by reference to the accompanying drawings illustrating preferred embodiments of the invention in which the reference characters refer to like parts throughout the several views, and in which:

FIG. 1 is an elevational view of a preferred vehicle coil spring mounting, shock absorber, and encircling coil spring under compressive load, with a preferred adjuster device of the present invention installed be tween adjacent coils;

FIG. 2 is a perspective view of an unloaded coil spring with a preferred adjuster device of the invention installed;

FIG. 3 is a perspective view of a dual leaf adjuster device of the invention;

FIG. 4 is a cross-sectional view taken on the line 44 of FIG. 1 with the coil spring in phantom lines for clarlty;

FIGS. 5 through 8 are longitudinal cross-section diagrams of a preferred coil spring illustrating its characteristics respectively in its free height, under normal load at its manufactured spring rate, under normal load when the spring has lost its manufactured spring rate, and with a device of the invention installed to restore its spring rate;

FIG. 9 is a cross-sectional view illustrating a device of the invention as it is being installed between adjacent spring coils;

FIG. 10 is a cross-sectional view comparing the spring coils with lost spring rate and with the device of the invention installed to restore spring rate;

FIG. 11 is a fragmentary plan view of a sheet of material illustrating cutting lines for the no-waste manufacture of multiple strips from which devices of the invention may be formed;

FIG. 12 is a fragmentary perspective view of another stage in the manufacture of the device;

FIG. 13 is a plan view of another modification of the invention; and

FIG. 14 is a cross-sectional view taken substantially on the line 14-14 of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing and the following discussion of the present invention relate more particularly to its usage with vehicular suspension coil springs since development to date has concentrated in this area, but it will be apparent that the concepts are equally applicable to coil springs used in other devices and machinery. For example, the spring rate of coil spring shock absorbers used with many types of machines, railroad switchyard equipment, and the like, may be restored by installation of the present devices. Other uses may also occur where the cost of spring replacement or other maintenance can be saved by installation of devices embodying the invention.

Turning to the drawings, FIG. 1 illustrates a typical vehicular suspension coil spring 10 in compressed condition as mounted between upper and lower supports 12 and 14 and encircling a typical shock absorber 16.

An adjuster 18 is shown installed between adjacent coils 10a and 10b, spacing them greater than the spacing between other coils which have acquired an excessive compression set. It will be seen that the adjuster 18 will clear the shock absorber.

In FIG. 2, the spring 10 is illustrated in its normally unloaded free height with a five-leafed adjuster device already snapped in place. FIG. 3 illustrates a twinleafed device 18. In fact, one or any other number of leafs may be used, depending on the degree of spring rate restoration or lift desired.

As shown, each leaf comprises a strip 22 formed with an arcuate intermediate portion 220 and reversely arcuate end portions 22b which are formed to fit facing portions of the adjacent spring coils 10a and 10b. Multiple leafs 22 are joined, preferably at their midpoints, by preferably integral connector portions 22c. The portions 22a and 22b are, as seen, arcuate about axes extending substantially normal to the axis of the spring.

In the five-leaf version illustrated in FIGS. 2 and 4, the entire integral device is formed to the helix of the spring 10, locating the end and middle leafs 22 approximately 120 apart, with the other two spaced in between. If desired, a sixth leaf 22 may be provided as indicated by the phantom lines in FIG. 4.

In the event of installation difficulties, a multi-leafed adjuster 18 may be separated, by breaking one or more connector portions 22c since they have no loadcarrying function, into two or more parts.

Each leaf 22 provides a predetermined degree of lift or spring rate restoration to the coil spring 10 as a whole, so that any desired result may be obtained.

FIGS. 5, 6, 7 and 8 illustrate an exemplary function of the device in restoring spring rate. FIG. indicates a typical unloaded spring 10 having a free height A and normal coil spacing of 1 5/16 inch. Under a normal load of, for example, 1,000 lbs. (a typical automobile of 4,000 lbs. with four springs loads each about 1,000 lbs.), a new spring at a 400 lb./in. spring rate will then depress 2% inch as indicated in FIG. 6, the coil spacing being thereby reduced 9/32 inch to 1 l/32 inches.

However, as the spring loses strength and sags, for example as shown in FIG. 7, to take a one-half inch set, producing a 3inches depression under the same 1,000 lb. load, the spring rate is thus reduced to about333 lb./in. and the coil spaces will be reduced another three-thirty-second inch to thirty-one-thirty-second inch. Restoration to the 400 lb./in. spring rate requires that an adjuster device 18 of the present invention having a 467 lb./in. spring rate be installed as shown to lift the spring back the one-half inch and compensate for the sag, which can be effected with a three-leaf adjuster device in which each leaf has a spring rate of about 155 lb./in.

In actuality, a five-leaf adjuster formed from 0.0509 (17 GA.) SAE 1050 spring steel, hardened to about 47-49 Rockwell, has been manufactured, and found to have a 1,500 lb./in. spring rate (300 lb./in. rate per leaf), so that a much greater sag than that illustrated may be corrected quite readily, or the illustrated sag may be corrected using fewer leafs.

FIG. 9 illustrates how each leaf 22 is dimensioned to be readily inserted between the two coils 10a and 10b when the spring is unloaded (as in FIG. 5), with the vertical dimension of the arced portion 22a being just slightly greater than the spacing of the coils, so that it can be snapped into the phantom line position shown and be held by the end portions 22b against the facing coil surfaces. Under load, the arced portion 22a resiliently urges the ends 22b against the coils 10a and 10b to the solid line position, as shown in FIG. 10, from their otherwise compressed phantom line position indicated therein.

The adjuster device described in the foregoing also produces a variable rate spring which is useful in, for

example, vehicle rear coil suspension springs, since the resistance to compression of the coils engaging the adjuster 18 is greater than that of the other coils, so that under lighter loads a substantially normal spring function occurs, but resistance to heavy loads will be greater as the adjuster 18 is forced to compression after the other coils near their compression limits.

In normal use, even though the adjuster 18 is of relatively thin stock and might appear to be fragile, it will not flex a great deal upon compression since the greater part of the load is taken by the coil spring itself. In the case of new springs, the adjuster will act more as a spring lifter than as a sag resistance, since the proportion of the total spring rate attributable to the adjuster is relatively smaller than when used with a fatigued spring which has a much lower rate.

Also, additional adjusters 18, such as that indicated in phantom line in FIG. 8, may be used for greater load carrying needs, or to beef-up selected overly sagged coils of an otherwise normal spring.

FIG. 11 illustrates the no-waste cutting or stamping pattern in a sheet 30 of resilient material which will form a plurality of contiguous elements 32, each having similar multiple spaced leaf portions 32a joined by connector portions 32b, the leaf portions 320 of one element 32 being formed from that material which spaces the leaf portions 32a of adjacent elements 32, so that only small fragments 33 at the edges of the sheet 30 need to be scrapped.

The connector portions 3217 may be severed as desired to form adjuster blanks of any leaf multiples. The leafs 32a are then formed to the necessary shape as shown in FIG. 12 so that the ends are arced complementary to the radius of the spring coils with which they are intended to be engaged and are spaced from each other to properly engage adjacent spring coils, the element as a whole then being formed to the helix of the spring, thereby completing the adjuster device as previously described. Various adjuster devices for different uses or different springs may be made from identical blanks.

FIGS. 13 and 14 illustrate another possible embodiment of the invention in which individual single leaf adjuster devices 40 each comprises a double arched intermediate resilient portion 40a spacing end portions 40b dimensioned to the spacing of and arced to engage adjacent spring coils 42.

The portions 40a of multiple devices 40 are joined by a connector wire 44 formed to the helix of the spring coils 42 and substantially equally spacing the devices 40 as indicated in FIG. 13.

These devices 40 may each be formed from substantially rectangular blanks, any number of which are readily cut or stamped as contiguous elements from a sheet of material.

Although only a few embodiments of the invention have been shown and described herein, it will be apparent to one skilled in the art to which the invention pertains that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. An adjuster for a coil spring having a spring axis and a dimension between adjacent coil surfaces of the coil spring comprising a plurality of spaced strips of material each formed with its ends adapted to engage respectively facing surfaces of adjacent spring coils and strip intermediate portion by a connector means.

2. The adjuster of claim 1 wherein said connector means comprises an element formed integrally with said strips.

3. The adjuster of claim 1 wherein said connector means comprises a wire element affixed to said strips. l 

1. An adjuster for a coil spring having a spring axis and a dimension between adjacent coil surfaces of the coil spring comprising a plurality of spaced strips of material each formed with its ends adapted to engage respectively facing surfaces of adjacent spring coils and its intermediate portion adapted to flex resiliently resisting compression of said spring coils, said intermediate portion having outer dimensions taken on a line parallel to said spring axis being slightly greater than the dimension between said adjacent coil surfaces taken when said spring in uncompressed, the intermediate portion of each strip connected to its adjacent strip intermediate portion by a connector means.
 2. The adjuster of claim 1 wherein said connector means comprises an element formed integrally with said strips.
 3. The adjuster of claim 1 wherein said connector means comprises a wire element affixed to said strips. 